Food freezing tunnels have been in use for many years. In most tunnels food to be frozen is conveyed through the tunnel on a porous conveyor belt. Freezing air has been directed around the top and bottom of the belt by a side mounted fan, as illustrated in Frank W. Knowles' U.S. Pat. No. 2,385,140 disclosing his process of freezing food. Also the freezing air has been directed through the porous conveyor belt, as illustrated in various patents, such as Walter E. Hirtensteiner's U.S. Pat. No. 3,376,710 disclosing his food freezing apparatus having an overhead fan, or as illustrated in Willis S. McLeese's U.S. Pat. No. 3,425,237 disclosing his vibrating food freezer, having a lower fan, or as illustrated in another U.S. Pat. No. 2,300,229, of Frank W. Knowles, describing the freezing of peas having a side mounted fan.
In Mr. Hirtensteiner's U.S. Pat. No. 3,376,710, and in Mr. McLeese's U.S. Pat. No. 3,425,237, the air, discharging from the fans, is essentially moving directly toward the porous conveyor belt moving the food products through the freezing tunnel. Although less width is possible in arranging such freezing tunnels, in contrast to the freezing tunnels of Frank W. Knowles, the strong but non-uniform discharge of the cooling air directly from the fans has led to the irregular freezing of the food products being conveyed. In an attempt to gain a more uniform distribution of the cooling air, other persons, like Frank W. Knowles in his U.S. Pat. Nos. 2,300,229 and 2,385,140, have increased the width of their freezing tunnels to place the fan and its chamber off to one side, and then redirect the freezing air through the adjacent chamber in which the porous conveyor belt is carrying the foods being frozen. In other freezing tunnels currently in operation, fans with their volutes and shrouds are angularly mounted to one side of freezing tunnels, thereby requiring wider buildings or interior building spaces in an attempt to obtain more uniform freezing air distribution.